Telephone-relay.



i No, 781,207.

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W. W. JACQUES. TELEPHONE RELAY.

APPLIOATION FILED Nov. a, 1904 .5@ WIT E?, E E E.

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To @ZZ whom it may concern.-

i UNITED STATES Patented January 31, 1905.

vPATENTy OFFICE.

TELEPHONE-RELAY.

SECIFICATION forming part of Letters Patent No. 781,207, dated January 31, 1905.

Y' Application led November 3, 1904. Serial No- 231,275.v

vBe it known that I, WILLIAM JACQUES, of Boston, in the State of Massachusetts, have invented a new and useful Improvement in Telephone-Relays, of which the ,following is a specication. In vLetters Patent No. 767,818, issued to m on August 16, 1904, Ihaveshown ho'w we may by balancing the product of the telephonie resistance and capacity of a circuitby the product of its telephonic inductance and shuntage provide a telephone-circuit over which conversation may be carried on without distortion of the speech-and with a minimum loss in loudness. Such a circuit yis called a distortionless circuit. In a .distortionless circuit, however,as in all telephone-circuits, there is a gradual attenuation or enfeeblement of the electrical undulations or telephone-Waves as they pass along the circuit from the near end, where the telephone-transmitter converts the speakers Vocal utterances into telephonewaves, to the distant end, where the telephonereceiver recouverts these telephone-waves into vocal sounds to fall upon the listeners ear. On very long circuits this attenuation may be so extremethat the enfeebled waves' are unable to satisfactorily operate the receivingtelephone, so that' conversation over such av circuit becomes unsatisfactory or impossible. This attenuation is not directly proportional to the distance traversed by the Wavesthat is, the intensity of the wave is not one-half as great at a distance of two thousand miles as which makes the waves so 'feeble that con-rrr versation is quite impossible. I f,`however, at the end of "o'e thousand miles we can restore the w-avesfto theiroriginal intensity, then the attenuation for` the whole two thousand miles will be only to one one-hundredand-ftieth, so that good commercial conversation maybe carried on over the whole two thousandmiles.

It has been proposed to reinforce telephonewaves by inserting into the circuit a relay consisting of a magneto telephone-receiver whose diaphragm acts upon ,a microphone so thatl by the introduction of fresh energy from the battery of the microphone the telephonewaves in the receiving-telephone' circuit are magnified in the microphone-circuit. Experience shows that such simple relays are of little practical use, vand I find the reason is y the speech becomes shrill and inarticulate, so

that conversation is quite impossible.

I have made in mylaboratory extended studies of the vvariation of resistance of microphone-contacts with pressure and of the magnification oftelephone-waves by 4microphones adjusted to various normal pressures, and from these studies I have found that for 'very light normal pressures the microphonic resistance'varles more than proportionately to the variation of pressure, so that the ini tensity of the waves is rgreatly magnified; but the shape of the waves is greatly distorted, because thehigh-pitch waves are much more magnified than are the low-pitch waves.v On

`the other hand, with heavy normal pressures there is comparatively little magnification; but the shape of the waves is again distorted,

now in the other direction, because the lowpitch waves are now magnified more than the high-pitch waves; I find that `the yrange of normal pressureI over which there is no distortion of the waves is very limited and that kwithin these limits the magnification is very small.

I have discovered that by the use of two relays, each consisting of a receiving-tele- IOO phone and a microphone, the receiving-telephone of the second being connected in circuit with the microphone of the first, the one relay having its parts delicately constructed and its normal pressure made exceedingly light, while the other relay has its parts more massive and its normal pressure heavier, the first relay being used, essentially, to magnify the telephone-waves, while the essential funetion of the second relay is to correct the distortion of the first, (though each multiplies the magnification and each corrects the distortion of the other,) I may by thus introducing fresh energy at one or more points along a telephone-circuit restore the enfeebled waves at these points to their original intensity or even more, if desired, and without resultant distortion of their shapes, and I may even correct a not too serious distortion in shape that the waves may have suffered from transmission over a long circuit which is only approximately distortionless. A magnifying-relay and av correcting-relay thus associated I will call a compound relay.

By the introduction of one or more com- :pound relays into even very long telephonecircuits of the distortionless or approximately distortionless type conversation may be carried on even between widely-separated stations without serious loss either in loudness or clearness of articulation.

The operation of my compound relay may be appropriatelylikened to the operation of acompound microscope, the strongly-magnifying but distorting relay being analogous to the strongly-magnifying but distorting objective of the microscope, while the more feebly magnifying but correcting relay is analogous to the more feebly magnifying but correcting eyepiece of the microscope. As in the compound microscope, so in the compound relay, While neither objective nor eyepiece is capable of yielding considerable magnification without distortion, objective and eyepiece combined enable us to obtain very great magnification without resultant distortion. In the compound microscope, as in the compound relay, each lens (or relay) magnifies, each multiplies the magnification of the other, and each `corrects the distortion of the other. As in the microscope additional lenses may be inserted between the objective and the eyepiece to increase the magnification, lso in the compound relay additional relays may be inserted between the magnifying and the correcting relay with similar effect.

My invention is `founded upon my abovestateddiscoveries; and it consists, primarily, in the compound magnification and the correction of 'telephone-waves by the association of two or more relays, as above described, and as hereinafter more fully described.

My invention further consists in means for so connecting two or more such compound relays to the Wires of thev main'telephone-circuit as to magnify and correct telephone-waves transmitted over the circuit in either direction. Two compound relays associated together, one of which operates in one direction along the line while the other operates in the other direction, will be here called a telephone-repeater.

My invention further consists in various details presently to be described.

lIn the drawings, Figure l is a view of my compound relay shown as inserted midway of a telephone-circuit, the connecting-wires and auxiliary parts being shown diagrammatically. Fig. 2 is a horizontal cross-section of the magnifying-relay, showing the essential details of construction. Fig. 3 is a front view of the microphone of the magnifyingrelay as presented to the diaphragm of its receiving-telephone. Fig. 4 is a side view, partially in cross-section, showing such details of construction of the correcting-relay as are different from those of the magnifying-relay. Fig. 5 is a front view of the microphone of the correcting-relay as presented to its receiving-telephone. Fig. 6 is a diagram showing two compound relays so associated with each other and midway of a telephone-circuit as to make a telephone-repeater.

So far as may be the same letters refer in all figures to like instruments, apparatus, wires, &c., numerals being added to the letters to designate different parts of the same kind and the letters sometimes being coupled. Thus T in all cases indicates a set of telephone apparatus, t a telephone-transmitter, and fr a telephone-receiver. B indicates a battery, w a wire, odd numbers being usually affixed to indicate parts of the apparatus operative in one direction and even numbers parts in the other direction. Numerals are sometimes used independently of letters to indicate parts of instruments or circuits and letters are sometimes used without numerals to refer generally to parts which are particularly designated by the same letter with the numeral attached.

To avoid confusion, so much of the apparatus only is shown in the drawings as will enable the invention and its mode of operation to be understood.

In Fig. 1 the relay is shown as inserted m'idway between telephone-stations T and T, which may be assumed to be two thousand miles apart. As here shown, it is arranged to magnify the telephone-waves, which, originating at T', have passed one thousand miles over the circuit w and w to the compound relay R3 and having been magnified and corrected by that relay to send them along the circuit 202 and w* another one thousand miles to the distant telephone-station T.

Rm3 is the magnifying-relay, and it consists of the receiving-telephone r3 and the transmitting telephone or microphone t. The receiving-telephone is essentially like that in ICO IIO

`general use'bythe American Telephone and.

VTelegraph Company, excepting that its diaphragm dp, Fig. 2, is preferably held be tween concentric annular knife-edges im lm, Iso that the spring of the diaphragm is opposed to the pull of the magnet. 1 find that this method of supporting the diaphragm increases its sensitiveness and accuracy of .vibration in a marked degree. c Y

The transmitting telephone or microphone t3, Fig. l, of -the relay Rm consists of a granular-button microphone Q62, such asis in common use 1n the long-distance transmitters ofr the American Telephone and Telegraph Company, which granular buttonis fixed in the lead ball W on the side toward the diaphragm dps and is counterbalanced by a weight 053. The lead ball possesses considerable inertia.

1t is supported from the adjustable support @s2 by the bifilar suspension-wires w and p07, so that it is free tomovetoward or from the diaphragm, but not inotherdirections. suspending-wires also serve as lead -wires.

The telephone r3. slides freely on an iron bedplate Bp and may be adjusted to very delicate contact with the granular button, so as to produce .an exceedingly delicate light-pressure multiple-contact microphone within thev granular button. At the same time the lead ball presents a considerable inertia to the vibrations of the diaphragm The microphone-circuit is completed by the `battery B3, the primary of the induction-coil 103, and the connecting-wires, as shown. The secondary circuit of the 'coil 103 leads directly to the receiving-telephone p5 of the correctingrelay.

The correcting-relay R05 is, in general, like the magnifying-relay Km2, excepting that it is-more massive in its construction and operation, Figsf and 5. The magnetisstronger,

the diaphragm is larger and thicker, Aand the` inertia of the granular button i's much greater.

,When in operation, the pressure between its diaphragm and the granular button g', F ig.,

ondary of 105 should have many turns, as is customary with coils connected directly to long circuits.

The operation of the `compound relay R3 asa whole is as follows: Telephone-Waves from station T having traveled, sayone thousand miles, and having become attenuated, say, to one one-hundred-and-liftieth of their original intensity, which still leaves them quite strong enough to actuate the relay telephone-receiver r3, but far too feeble to continue unaided an-` other one thousand miles to operate the receiverof station'T2, by actuating the receiv- .The

- ing-telephone r3 of the magnifying-relay, Rms, set its diaphragm in vibration. These vibrations. are bymeans of the light pressure and heavy inertia microphone t3 reproduced greatly magnified andfsomewhat distorted in the circuit w 'a02 w w, vwhich leads to the receiving-telephone p2 of the correcting-relay R02. 1n virtue of theheavy pressure and inertia of the microphone tvof the correctingrelay the magnified and distorted waves are again magnifiedand this time corrected, so that they are now reproduced onI the farther line-circuit 102 fw, restored to the original intensity, and corrected to the original shape with which they left the station T, and therefore ready to enter on the second stage of their long .journey to the distant station T2.

By sliding the receiving-telephones p3 and p5 of the compound relay along the surface of the heavy iron bed-plate Bp the respective microphone-contacts may beeach adjusted to thedesired efiiciencyand each may bead- `justed'to best'coperate with the other to secure the desired .magnification and correction of distortion. .The bed-plate Bp is preferably supported. by a springy pad Sp, so that its weight, together with the springiness of thepad, protects the apparatus from extrane- Ousmechanical vibrations. '1t should beinclosed by a reasonably sound-proof cover to protect it from extraneous acoustic vibrations. Y 1tis evident that while the compound. 1elayfasthus far described is capable'of magnifying the sounds'uttered into the telephone at station T so that they will be heard in the telephone at station T2, sounds uttered .at lT2 cannot be heard at T-z'. 0., the relay will not work both Ways over the same circuit.

1f we connect the wires lw w3 Aof the first one thousand miles of circuit directly with the wires a02 wL of the second l one thousand miles of circuit or, vwhat is the same thing, bridge both the receiving-telephone of the magnifying-relay and .the transmitting-telephone of the correcting-relay both between the two main circuit-wires extending from T to T2, we find'that the magnified waves are not only sent to line', `but also into the receiving-telephone of the magnifier itself, where IOO IIO

they are of course again magnified, and this cycle of reinforcements is kept upwith increasing strength until the Vdiaphragms are forced to their elasticlimits, when-they continue to vibrate violently and give out a loud roaring sound, determined by the normal times of vibration ofthe diaphragms and the associated circuits, which i-n no way resemblesarticulate speech.

We may, indeed, employ two complete metallic circuits extending from stati'ongT to station T2 and by inserting a compound relay -in the middle of each circuit, each relay being inserted to operate inthe desired direction, carry on a conversation between T and T2; but this would be expensive. In practice we may do better than this and substitute for the half of each circuit beyond the relay an inexpensive artificial circuit having the same electrical properties as the actual line on the nearer side of the relay, and then conneet the outgoing circuit of each compound relay differentially through the receiving-telephone of the opposing relay. l/Ve thus have merely a single metallic circuit extending between stations T and T2, with a repeater composed of two opposing compound relays and two inexpensive artificial lines inserted midway of the circuit, and over such a circuit we are enabled to carry on a loud and clear conversation. Such an arrangement of circuits is shown diagrammatically in Fig. 6. In addition to such parts as have already been designated, AZ and AZ2 are artificial lines having approximately the same distributed telephonie resistance, capacity, inductance, and shuntage as the actual lines with which they are directly connected.

The receiving-telephones 717 and 918 are added to preserve the balancing of the lines. They may be simply dummy relays-z'. e., receiving-telephones without accompanying microphones-or they may be merged, respectively, into 'r3 and r4 by placing the windings of 717 and rs upon the same magnets as r3 and of* or by allowing the two magnets of each relay to act upon the same diaphragm.

The operation ofl the repeater as a whole is as follows: Telephone-waves from station Tl pass, say, one thousand miles over the actual line w w3, through the two coils of the receiving-telephones r3 717 of the relay R3, and then through the artificial line AZ'. The outgoing waves from the relay R3, now restored to their original intensity, more or less, as desired, pass by wires w17 w1 to the middle points of the receiving-telephones r* and rg of the relay Rf, and the artificial line AZ2 presenting the same electrical properties as the actual line 202 w4 these waves act equally and oppositely upon each of the receivers r4 and frs, and so produce no effect upon the relay R; but they do act upon the telephone at station T2. The loss of energy due to division of the waves between the artificial line and the actual line is only one-half, which with small line attenuation and large relay magnification is a loss that in no way affects the commercial operation of the line. If desired, connection may be made to the receiving-telephones r4 rs not at the middle point of the coils, but between that point and one end, and then the artificial line may be made a miniature of the actual line in accordance with the well-known principle of the VVheatstone bridge.

Having thus described the operation of the repeater in the direction from station T to station T2, its operation in the opposite direction from station T2 to station T will from the symmetry of the diaphragm and the abovedescribed nomenclature be readily understood. Each compound relay of the repeater magnifies and corrects in its own direction, and each acts diiferentially upon its mate.

The above-described telephone-relay is especially adapted. to be used in connection with circuits of the distortiouless type, although` because of its above-described power of correcting a not too serious line distortion it may be used in connection with approximately distortionless circuits. The telephoneengineer to whom this specification is addressed will readily determine how far a given line may depart from the strict requirei'nents of an ideal distortionless circuit and still be capable of satisfactory relaying if he will read in this connection my Patent No. 767,818, of August 16, 1904, referred to at the beginning of this specification.

I claim- 1. A compound telephone-relay composed of a magnifying-relay and a correcting-relay, the magnifying-relay consisting of' a sensitive receiving-telephone in circuit with the incoming section of' the line and adjusted to exert a light normal pressure upon the contacts of a sensitive microphone, the correcting relay consisting of a more massive receiving-telephone in circuit, electrically, with the microphone of the magnifying-relay, and adjusted to exert a heavy normal pressure on the coutacts of a heavy inertia microphone whose circuit is connected, electrically, to the outgoing section of' the line.

2. A compound telephone-relay consisting` of a magnifying-relay and a correcting-relay, the magnifying-relay consisting of a receiving-telephone in circuit with one section of the line, and a microphone adjusted to light normal pressure; the correctingrelay consisting of a receiving-telephone in circuit electrically with the microphone of the magnifying-relay, and a microphone adjusted to heavy normal pressure and having its circuit connected electrically to the other section of the line.

3. A pair of microphones, one adjusted to light normal pressure and the other adjusted to firm normal pressure, each provided with a separate primary circuit and a source ol eleetromotive force therein, the one adjusted to light normal pressure having also a secondary circuit and a magnet therein adapted to vary the vibrations in said firm-pressure microphone according to vibrations set up in said light-pressure microphone.

4f. A pair of' microphones, one adjusted to light normal pressure and the other adjusted to firm normal pressure, each provided with a separate circuit and a source of eleetromotive force therein, the one adjusted to light IOO TIO

5. In combination with a telephone-circuit the product of whose telephonic resistance and capacity is substantially balancedby the product of its telephonie inductance and shunt- '5 age., one or moretelephone-relays inserted in the circuit at one 4or* more points, whereby the attenuation of the telephone-waves traveling along the circuit is reduced `or eliminated.

6. In combination with a telephone-circuit in which the telephone-waves are more or less distorted, a` telephone-relay adjusted to produce inverse distortion, whereby the resultant telephone-waves are undistorted.

7 A telephone-repeater composed of two opposed telephone-relays, the incoming circuit of each being connected in series between one section of the line and a similarly-dimenl sioned artificial line while its outgoing circuit 2O is connected differentially through the receiving-telephone of the other and thence in multiple through the other section of the line and vasimilarly-dimensioned artificial line.

8. LFour microphones arranged in pairs,

25 each pair consisting of a microphone adjusted to light normal pressure and another microphone adjusted to firm normal pressure, each microphone of each pair being provided with a separate circuit and a source of electromoelectrical dimensions, an apparatus for magnifying the intensity and correcting the shape of telephone-waves.

` 10. Adistortionless and non-attenuating telephone-circuit consisting of two line-wires divided into sections, each section having the product of its resistance and Vcapacity substantially balanced by the product of its resistance and shuntage and being provided with a similarly-dimensioned artificial circuit, and having telephone-repeaters inserted between each two sections, each repeater having'its incoming circuits in seriesand its outgoing circuits in multiple between the adjacent section and its artificial circuit.

y WILLIAM JACQUES. Witnesses: i. l

REUEN L. RoBERTs, BELLE L. RUGGLES. 

